<template>
  <el-card class="box-card">
    <div slot="header" class="clearfix">
      <span>更换头像</span>
    </div>
    <div>
      <!-- 图片，用来展示用户选择的头像 -->
<img :src="avatar" alt="" class="preview" v-if="avatar"  />
<img src="../../../assets/images/avatar.jpg" alt="" class="preview" v-else />
      <!-- 按钮区域 -->
     <div class="btn-box">
<input type="file" accept="image/*" style="display: none;" ref="iptRef" @change="onFileChange" />
<el-button type="primary" icon="el-icon-plus" @click="chooseImg">选择图片</el-button>
<el-button type="success" icon="el-icon-upload" :disabled="avatar === ''" @click="uploadAvatar">上传头像</el-button>   </div>
 </div>
  </el-card>
</template>

<script>
export default {
  name: 'UserAvatar',
  data () {
    return {
      avatar: ''
    }
  },
  methods: {
    chooseImg () {
      // 模拟点击行为
      this.$refs.iptRef.click()
    },
    onFileChange (e) {
      const files = e.target.files
      if (files.length === 0) {
        this.avatar = ''
      } else {
        // 1. 创建 FileReader 对象
        const fr = new FileReader()
        // 2. 调用 readAsDataURL 函数，读取文件内容
        fr.readAsDataURL(files[0])
        // 3. 监听 fr 的 onload 事件
        fr.onload = e => {
          // 4. 通过 e.target.result 获取到读取的结果，值是字符串（base64 格式的字符串）
          this.avatar = e.target.result
        }
      }
    },
    // 上传用户头像
    async uploadAvatar () {
      const { data: res } = await this.$http.patch('/my/update/avatar', { avatar: this.avatar })
      if (res.code !== 0) return this.$message.error('上传头像失败！')
      this.$message.success('上传头像成功！')
      this.$store.dispatch('user/initUserInfo')
    }
  }
}
</script>

<style lang="less" scoped>
.btn-box {
  margin-top: 10px;
}
.preview {
  object-fit: cover;
  width: 350px;
  height: 350px;
}
</style>
